The recent proliferation of secondary storage devices has made it possible to store mass amounts of information on computer systems. Information that resides on any given computer system may include user documents which change over time and more static information such as encyclopedias and dictionaries. The ability to gain access to such a large amount of information coupled with the multiple view capability provided by today's user interfaces (i.e., window generating applications) allows computer system users to view viewable objects which are extremely large in size and to view and/or edit multiple viewable objects simultaneously. The extreme size of today's viewable object often leaves users wondering where they are and where they have been within even a single viewable object. This problem is exacerbated when the user needs information from several viewable object at the same time.
For example, a user may be viewing a document which is in the process of being written when he or she decides to incorporate a line from a famous poem. Since the computer system has the text of the poem stored in secondary storage (most likely on an optical storage device), the user simply accesses the work, selects the appropriate text, and incorporates that text into the document. But this power is not limited to two viewable objects. In the process of writing the document, the user may need more and more information (e.g., a dictionary to define a term or an encyclopedia to include explanatory text).
After a while, there may be several viewable objects being presented to the user at the same time. At some point, there is so much information being represented in so many windows that it becomes impossible for the user to determine what view is currently being presented for what object. This, of course, causes the user a great deal of consternation. The user ends up "fishing around" in each viewable object trying to find where they were and where they want to go.
One contemporary attempt at solving this problem is the use of "book marks." Much like the common use of a slip of paper to mark a particular place in a book, the computer styled book mark is a visual representation of a particular location within a viewable object. A user can place the book mark at a particular location and then return to that location by accessing the book mark. Book mark facilities have two serious short comings. First, book marks, as visual representations of location, are effective only when they can be seen by the user. When several views of viewable objects are being simultaneously presented to the user, the windows used will invariably overlap. Since book mark facilities depend upon the user being able to see the outer portion of the window that contains the viewable object, the user is often unable to see and, therefore, use the book mark. This problem is especially acute when one considers the needs of visually impaired computer users.
The second shortcoming of book mark facilities is that they depend upon user intervention to accomplish their function. If the user does not mark a position within the viewable object, no location information is available to the user. Book mark implementations provide no way for the user to determine where they are relative to the whole viewable object (i.e., relative to the top and the bottom) or where they are relative to frequently used portions of the viewable object. Scroll bar facilities do provide an indication of where the user is relative to the whole of the viewable object, but they too depend upon visual representations. As mentioned above, this leads to user confusion when windows overlap and is totally unworkable for the visually impaired computer user.